Two children have been infected by new types of swine flu. Unlike flu viruses in the past that have jumped from pigs to humans, these have a gene from the pandemic 2009 H1N1 (swine) flu. The CDC is continuing to investigate, but so far no other cases have been reported.
The infections occurred in children under five. The first case occurred in late July when an Indiana boy with multiple chronic conditions had fever, cough, shortness of breath, diarrhea, and sore throat. He was briefly hospitalized but has since recovered. While he reported no contact with pigs, a household caretaker did.
The other case occurred in a Pennsylvania girl in late August after she had been exposed to pigs at a county fair. She experienced fever, cough, and lethargy, but has also completely recovered. Both children had received the 2010 seasonal flu vaccine.
The viruses found in the two cases aren't identical, and the two cases have not been linked.
The new cases this year are similar to an outbreak of a new H1N1 virus in California in April 2009 that later became a pandemic flu. But that doesn’t mean that this virus will follow the same path.
Bottom line. Flu viruses often mutate and jump between species, including from pigs to humans. But when that happens, it’s uncommon for the virus to then spread from human to human. At this point, it’s still unclear whether the new H1N1 virus can be transmitted among humans, so it’s far from a promise of another flu pandemic.
In related news, the CDC announced today that the Food and Drug Administration approved a new laboratory diagnostic kit to “diagnose human infections with seasonal influenza viruses and novel influenza A viruses with pandemic potential.” So if this virus does develop into a threat, there will be better tools available to identify and track its spread.
Sources: Swine-Origin Influenza A (H3N2) Virus Infection in Two Children --- Indiana and Pennsylvania, July--August 2011[CDC]